The invention relates to the preparation of alkyl tin halides by means of direct conversion of an aliphatic halide with a stannous halide in the presence of a nitrogenous compound and of iodine and/or a iodide as a catalyst.
According to prior art two types of direct synthesis reactions are known:
A. REACTION OF METALLIC TIN WITH AN ALKYL HALIDE UNDER THE INFLUENCE OF A CATALYST,
THIS REACTION, FOR WHICH IN THE (PATENT) LITERATURE A GREAT VARIETY OF CATALYSTS HAS BEEN DESCRIBED, LEADS TO THE FORMATION OF DIALKYL TIN HALIDES AS MAIN PRODUCT, TOGETHER WITH TRIALKYL AND/OR MONO ALKYL TIN HALIDES AS BY-PRODUCT(S)
B. REACTION OF A STANNOUS HALIDE WITH AN ALKYL HALIDE UNDER THE INFLUENCE OF A CATALYST.
For this reaction (b), which according to the literature leads to the formation of mono alkyl tin halides, also a number a catalysts has been described in the (patent) literature, such as, for instance, with compounds of bivalent sulphur and/or selenium, or also with amines as catalysts (in quantities of 0.01 - 2% by weight), whether or not combined with the addition of slight amounts of iodide and/or inorganic iodides.
These reactions are in particular carried out in an autoclave upon application of the low boiling methyl, propyl and butyl halides and then require a heating time of many hours.